Section 2-8: Speeding up a Chemical Reaction

Section 2.8—Speeding Up A Reaction :Section 2.8—Speeding Up A Reaction How can we make those antacid reactions occur faster?


Kinetics & Reaction Rates :Kinetics & Reaction Rates Kinetics – Study of the rates of reactions Reaction Rate – Rate at which reactants produce products


Collision Theory :Collision Theory Collision Theory – Defines 3 circumstances to be met for a reaction to occur. Reactants must collide Collision must be at the correct orientation Collision must have minimum energy for reaction to occur 1 2 3 Only a small number of collisions meet the requirements and result in a reaction


Collisions Must Occur :Collisions Must Occur In order for two molecules to react, they must come in contact with one another There’s no way they’ll ever react if they don’t run into one another!


Collision with Correct Orientation :Collision with Correct Orientation For a collision to result in a chemical reaction, it must occur with the correct orientation This is not the correct orientation. The reaction will not happen.


Collision with Correct Orientation :Collision with Correct Orientation For a collision to result in a chemical reaction, it must occur with the correct orientation F This is the correct orientation. The reaction will happen.


Collision with Enough Energy :Collision with Enough Energy For a collision to result in a chemical reaction, it must occur with the minimum energy for reaction The collision does not have enough energy to produce a reaction


Collision with Enough Energy :This collision had more energy (faster moving molecules). A reaction will occur.. Collision with Enough Energy For a collision to result in a chemical reaction, it must occur with the minimum energy for reaction F


Activation Energy :Activation Energy Minimum energy for reaction to occur during a collision


Factors Affecting Reaction Rates :Factors Affecting Reaction Rates


Surface Area of Reactants :Surface Area of Reactants How does the surface area of the reactants affect the reaction rate? Reactants must collide in order to react Larger surface area means more particles can come in contact with each other at the same time More reactants can collide at the same time and a fraction of those will result in reaction As surface area increases, reaction rate increases


Concentrations of Reactants :Concentrations of Reactants How does the concentration of reactants affect the reaction rate? Only a small fraction of the collisions meet the requirements and result in a reaction More reactants mean more collisions will occur If more collisions occur, more will meet the requirements and result in a reaction As reaction concentration increases, reaction rate increases


Temperature :Temperature How does temperature affect the reaction rate? Reactants must collide with at least energy equal to the activation energy If molecules are at a higher temperature, they have a higher average kinetic energy With higher energy molecules, collisions will have higher energy and more often result in reaction For most reactions, as temperature increases, reaction rate increases


Catalysts :Catalysts Catalysts – Substance that increases the rate of reaction without being used up A + B + C  D + C “C” is the catalyst…it is present in the beginning and in the end Enzymes are catalysts in the body


Catalysts :Catalysts How do catalysts help speed up the reaction without being used? They increase the chances that a collision will successfully produce a reaction For example, catalysts hold one or more of the reactants in place to allow collisions to occur with the correct orientation Once the reaction has occurred, the catalyst releases the molecule(s) and finds another one to help


What did you learn about antacids? :What did you learn about antacids?


Antacids :Antacids Mixture Compounds Chemical Formulas Collision Theory Acids & Bases Chemical Reactions Balanced Chemical Equations